Medical personnel have to exercise the utmost of care when using conventional syringes so as not to be accidentally punctured by a contaminated syringe needle resulting in possible exposure to infectious diseases, such as acquired immune deficiency syndrome (AIDS) or serum hepatitis when injecting a medicament into a patient.
While various safeguards have been provided, such as protective caps for covering a used needle and sharps containers for the disposal of the used needle, it has been found that the chance of accidental puncture is most likely to occur during the manipulation of the syringe to either cap the needle or inverting the used needle into the sharps container.
In an effort to improve the safeguards for used syringe needles, it has been proposed to provide the syringe with a sleeve slidably mounted on the syringe barrel and movable from a retracted position on the syringe barrel to an extended position at the distal end of the barrel, to thereby provide a shield surrounding the used needle. The sleeve is releasably held in the retracted and extended positions by detents which are manually actuated by the user. These sleeve-type shields have not proven entirely satisfactory due, mainly, to the manual dexterity required by the user to release one detent for sliding the sleeve to the needle protecting position and then to actuate another detent for holding the sleeve in the extended position.
In order to overcome the disadvantages experienced in hitherto employed shielded medical syringes, the disposable shielded medical syringe of the present invention has been devised which comprises, essentially, a syringe barrel including a plunger having a piston on the end thereof slidably mounted in the barrel. The syringe needle is connected to a second piston slidably mounted within the barrel and located between the distal end of the barrel and the plunger piston. By this construction and arrangement, medicament is dispensed from the syringe by pushing the plunger toward the distal end of the barrel, and the needle and associated piston are drawn inwardly into the barrel when the plunger is pulled back toward the proximate end of the barrel, whereby the used needle is shielded by the syringe barrel. To complete the shielding of the used needle, a cap or scabbard is inserted into the distal end of the syringe barrel. Vent holes and an associated closure are provided on the distal end portion of the syringe barrel, whereby the vent holes are closed during the dispensing of the medicament from the syringe and opened during the retraction of the syringe plunger to thereby facilitate the drawing of the used needle and associated piston to the shielded position within the syringe barrel.
A spring clip is mounted on the proximate end portion of the syringe barrel providing a stop member to prevent the syringe plunger from being pulled completely out of the barrel.
The medical syringe of the present invention thus provides a disposable shielded syringe needle requiring minimal manipulation to move the used needle to the shielded position thereby providing an improved safeguard for medical personnel against exposure to infectious diseases.